Knowing in detail the effects of a biostimulant on a crop makes it possible to guide formulation development, optimize product performance, evaluate its possible application on other crops, and identify other potential functions.Here are the steps to take to evaluate the effectiveness of a biostimulant. Authors: Giacomo Cocetta, Department of Agricultural and Environmental Sciences - Production, Territory, Agroenergy, University of Milan and Marta Guarise, Project Manager Training & Consulting of Agricola 2000